1. Field of the Invention
This invention relates to portable computers, and more particularly relates to circuitry which interfaces with portable computers. Even more specifically, this invention relates to a method and apparatus for concurrently transferring data between a host device and a plurality of pen based portable computers.
2. Description of the Prior Art
Pen based computers, which are commonly referred to as electronic clipboards, have become increasingly popular forms of portable computers. Such computers basically include a liquid crystal display and an integral tethered pen for hand-written input of information on the display. The pen based computer may be programmed to display a form or a chart with blanks provided for completion by the user who hand writes the information in the appropriate places on the form displayed. Such pen based computers are particularly adapted for use by non-technically trained personnel, as the user merely has to follow the form or instructions displayed on the computer. These pen based computers may be used by an electric utility, for example, by its meter readers, or may be used in a power plant or manufacturing facility, where gauges may have to be periodically monitored and their readings recorded.
The information inputted by the user to the pen based computer is retained in a memory or storage device in the computer until the data is transferred to a peripheral printer or main computer for analysis or display. The user, who is typically not technically trained, may find it difficult or not understand how to connect the pen based computer to the peripheral equipment or main computer and activate the main computer and pen based computer to output or "dump" the data. If an incorrect procedure is followed in transferring the data, some of the data may be irretrievably lost. Accordingly, either the user must be technically trained to carry out the procedure, or a computer operator must become involved in the data transferring operation.
Furthermore, such data transfer operation usually occurs on an individual basis. That is, only a single pen based computer is connected to the main computer at a time. This, of course, may cause the data transfer operation to take a considerable amount of time, especially when a plurality of pen based computers need to have their data transferred to the main computer.
Similarly, charging the batteries in the pen based computers and transferring data into the pen based computers from the main computer is done on an individual basis, one computer at a time.